Method and device to remove pipe

ABSTRACT

A pipe removal method includes navigating a flexible element through a first pipe. At least a portion of the flexible element is coupled with the first pipe. The flexible element and the first pipe are pulled as a composite assembly, and the flexible element reinforces the tensile strength of the first pipe. In one example, the first pipe is at least pulled in compression between the point of coupling between the flexible element and the first pipe and a proximal end of the flexile element. In another example, the method includes wrapping the composite assembly around a spool. The composite assembly is thereby removed from the ground surrounding the first pipe.

PRIORITY APPLICATIONS

This patent application claims the benefit of priority, under 35 U.S.C.Section 119(e), to U.S. Provisional Patent Application Ser. No.60/762,754, filed on Jan. 27, 2006, which is incorporated herein byreference.

TECHNICAL FIELD

Pipe replacement and in particular assemblies and methods for removingexisting pipes and positioning replacement pipes.

BACKGROUND

Pipe, such as plastic, copper, lead pipe and the like, has been used forconnecting homes and creating networks for utilities, for instance,water, sewage and natural gas. As pipes become older, they break down,crack, develop scaling on interior surfaces that can clog the pipe, etc.and thereby require replacement.

A technique known as pipe bursting is currently used as a method toreplace underground pipe without the need to completely dig up the pipeto be replaced. A pipe breaking device, such as an expander or a mole,is pulled by a cable through the existing pipe while it is stillunderground. The expander is designed to break, split or burst the pipe,and at the same time to push the old pipe into the surrounding soil. Theexpansion of the old pipe allows the expander to pull a replacement pipeinto place.

In some situations, instead of leaving pipe in the ground it isdesirable to remove the pipe (e.g., where the pipe includes anenvironmentally hazardous material such as lead). Some pipe is ductile,such as lead or copper, and has a low tensile strength. Pulling onductile pipe to remove it from the ground may result in tensile failure,thereby leaving a portion of the pipe in the ground. The section of piperemaining is difficult to extract and may require excavation forremoval.

What is needed is a pipe removal system that provides an option of piperemoval in contrast to pipe bursting. What is further needed isconsistent removal of pipe without fracturing of the pipe. What is stillfurther needed is a pipe removal system capable of removing low tensilestrength pipe and replacing the pipe with a new pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of one example of a pipe removal assembly coupledwith a ground working implement.

FIG. 1B is a side view of the pipe removal assembly showing one exampleof a removable end plate.

FIG. 2A is a perspective view of another example of the pipe removalassembly with a drive system including a chain drive.

FIG. 2B is another perspective view of the pipe removal assembly with adrive system including a chain drive.

FIG. 3 is a perspective view of yet another example of the pipe removalassembly with a drive system including a planetary gear assembly.

FIG. 4 is a side view showing the pipe removal assembly in one exampleof operation.

FIG. 5A is a perspective view showing the pipe removal assembly with apipe partially coiled around a spool.

FIG. 5B is a perspective view showing the pipe removal assembly with thepipe coiled around the spool.

FIG. 5C is a perspective view showing the pipe removal assembly with thecoil of pipe ejected off of the spool by a push plate.

FIG. 6 is a block diagram showing one example of a method for removingan in-ground pipe.

FIG. 7 is a block diagram showing another example of a method forremoving an in-ground pipe.

FIG. 8 is a block diagram showing yet another example of a method forremoving an in-ground pipe.

DESCRIPTION OF THE EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and that structuralchanges may be made without departing from the scope of the presentinvention. Therefore, the following detailed description is not to betaken in a limiting sense, and the scope of the present invention isdefined by the appended claims and their equivalents.

One example of a pipe removal assembly 100 is shown in FIG. 1A, 1B. Thepipe removal assembly 100 is shown attached to ground working implement102, such as the boom of a backhoe. The pipe removal assembly includes ahousing 101. The housing 101 has at least one feature sized and shapedto couple the pipe removal assembly 100 with the ground workingimplement 102. For example, the housing 101 includes a coupling plate103 sized and shaped to mate with the ground working implement 102. Theground working implement 102 optionally includes a complementary plate105 sized and shaped to mate with the coupling plate 102. In anotherexample, the housing 101 includes features (e.g., bolts, quick connectfasteners and the like) for coupling the pipe removal assembly 100 withthe ground working implement 102. Optionally, the pipe removal assembly100 includes a motor 104 sized and shaped to couple with hydraulic linesfrom the ground working implement 102. For instance, the motor 104includes, but is not limited to, a vane pump. While not necessary, theuse of a hydraulic motor 104 (e.g., a vane pump and the like) isadvantageous because of hydraulic accessory lines available on theground working implement 102, such as the boom of a backhoe. In anotherexample, the motor 104 is an electric motor, gas motor and the like. Themotor 104 is adapted to turn a spool and wrap a pipe 106 around thespool, as further described below. The motor 104 includes, but is notlimited to, a hydraulic motor such as a vane pump.

FIG. 1B shows a side of the pipe removal assembly 100 coupled with theground working implement 102. In one example, the pipe removal assembly100 includes an end plate 108 removably coupled with the spool. Asdescribed further below, removal of the end plate 108 permits access tothe pipe 106 wrapped around the spool. For example, removal of the endplate 108 permits ejection of the pipe 106 from the spool. Optionally,the end plate 108 is removably coupled with the spool with featuresincluding, but not limited to, bolts, quick connect fasteners, hook andcatch fasteners, cotter pins and the like. As shown in FIG. 1B, the endplate 108 is coupled to the spool (described below) with slots 110 sizedand shaped to receive pins 112 extending from the spool. The slots 110,in yet another example, include keyhole slots. The pins 112 have headswith a larger profile than at least a portion of the slots 110. The endplate 108 is removed from the spool by rotating the end plate (e.g., inthe clockwise direction as shown in FIG. 1B) so the pins 112 slipthrough the portions of the slots with larger openings, in anotherexample.

Another example of the pipe removal assembly 100 is shown in FIG. 2A.The spool 200 extends between a driving portion 202 and a wrappingportion 204 within the housing 101. In one example, the spool 200 is acylinder with a substantially circular cross section. As shown in FIG.2A, a pipe 106 is wrapped around a portion of the spool 200. The spool200 is constructed with materials having sufficient strength to pull andwrap the pipe 106 around the spool 200. For instance, the spool 200includes, but is not limited to, steel. The spool 200 is coupled with atleast one output sprocket 206 in the driving portion 202, in anotherexample. In yet another example, the spool 200 is coupled with two ormore output sprockets 206. For instance, as shown in FIG. 2B, the spoolis coupled with three output sprockets 206. In the driving portion 202,the pipe removal assembly 100 further includes an input sprocket 208coupled with the motor 104. Similarly to the output sprocket 206, in yetanother example, the pipe removal assembly 100 includes two or moreinput sprockets 208 (as shown in FIG. 2B). Using multiple pairs of inputand output sprockets 208, 206 facilitates the transmission of greatertorque to the spool 200 in a relatively inexpensive manner compared toother assemblies (e.g., such as direct drives and planetary gearassemblies). In still another example, the spool 200, output sprocket206 and the input sprocket 208 are rotatably supported in the housing101 by bearings (e.g., journal bearings, needle bearings and the like).The bearings are carried, in yet another example, substantially adjacentto a partition 210 that divides the housing 101 into the driving portion202 and the wrapping portion 204.

The input sprocket 208 transmits power from a motor, such as motor 104(FIG. 1A), along a drive chain to the output sprocket 206. Wheremultiple sets of output and input sprockets 206, 208 are used acorresponding number of drive chains extend between the sprockets.Referring again to FIG. 2A, in operation, the motor 104 (FIG. 1A)transmits power to the smaller input sprockets 208, then through thedrive chains, to the larger output sprockets 206 and the spool 200coupled thereto to generate a mechanical advantage therebetween (i.e.,increasing the pulling power of the output sprocket 206 at the expenseof rotational speed). In one example, the output sprocket 206 generatessufficient torque to pull at least around 30,000 pounds with the spool200.

Referring now to FIG. 3, in another example, the pipe removal assembly100 (FIGS. 1A, B) includes another mechanical advantage systemincluding, but not limited to a planetary gear system 300. The planetarygear system 300 shown in FIG. 3 is one example of a planetary gearsystem usable with the pipe removal assembly 100. In yet anotherexample, the planetary gear system 300 is rotatably coupled on a wall216 of the housing 101 shown in FIG. 2A. A sun gear (input gear) 302 ispositioned substantially at the center of the planetary gear system 300.Planet gears 304 surround at least a portion of the sun gear 302. Theteeth 306 of the sun gear 302 and the teeth 308 of the planet gears 304mesh so rotation of the sun gear 302 is transmitted to the planet gears304. A ring gear 310 extends around both the sun gear 302 and the planetgears 304, and the teeth 312 of the ring gear 310 are engaged with theplanet gears 304. Optionally, the ring gear 310 is coupled with thespool 200 (FIG. 2A). In another example, the spool 200 includes aninterior surface acting as the ring gear 310 including the teeth 312.

In operation, the mechanical advantage system is coupled between amotor, such as motor 104, and the spool 200. In one example, the motor104 shown in FIG. 2A is coupled with the sun gear 302. The sun gear 302transmits rotation from the motor 104 to the planetary gears 304. Theplanetary gears 304 transmit rotation from the sun gear 302 to the ringgear 310 and spool 200. Transmitting rotation from the sun gear to thelarger ring gear 310 generates a mechanical advantage. The pulling powerof the ring gear 310 is increased at the expense of rotation speed. Inanother example, the ring gear 310 generates sufficient torque to pullat least around 30,000 pounds with the spool 200. The planetary gearsystem 300 provides a mechanical advantage system that transmits hightorque and is also highly reliable.

Referring again to FIG. 2A, a push plate 212 extends around at least aportion of the spool 200 substantially adjacent to the partition 210.Optionally, the push plate 212 has an inner perimeter slightly largerthan the spool 200 and an outer perimeter larger than the spool. Inanother option, the push plate 212 extends around only a portion of thespool 200. The push plate 212 is moveably coupled along the spool 200and adapted to move over at least a portion of the spool 200. In yetanother example, the push plate 212 is coupled with at least onethrusting system 214 (e.g., a hydraulic cylinder and piston, compressedair actuator, electric actuator, manual actuator and the like) adaptedto move the push plate 212 along the spool 200. As shown in FIG. 2B, thepush plate 212 is coupled with three thrusting systems 214 including,for example, hydraulic pistons and hydraulic cylinders. The thrustingsystems 214 are coupled with the hydraulics of the ground workingimplement 102 (FIGS. 1A, B), optionally.

As shown in FIG. 4, the pipe removal assembly 100 is shown coupled tothe ground working implement 102. The ground working implement 102positions the pipe removal assembly 100 in a first trench 400substantially adjacent to a pipe 402. A flexible element 404 extendsthrough the pipe 402 and into at least the second trench 406. In oneexample, the flexible element 404 is navigated through the pipe 402 fromthe first trench 400 to the second trench 406. In another example, theflexible element 404 is navigated from the second trench 406 through thepipe 402 to the first trench 400. In yet another example, the flexibleelement 404 is coupled with the spool 200 (FIG. 2A) to facilitatewrapping of the flexible element 404 around the spool 200 as the spoolis rotated by a mechanical advantage assembly (e.g., one of theassemblies described above). Optionally, the flexible element 404includes, but is not limited to, a metal strand constructed with a smallnumber of wires. The advantages of using a metal strand include, but arenot limited to, the strand being relatively stiff for easy pushingthrough the pipe 402. Additionally, the small number of wires of themetal strand ensure the strand is relatively inexpensive and therebydisposable.

In another example, the flexible element 404 is a cable, chain, strip,ribbon and the like. In yet another example, the flexible elementincludes, but is not limited to, a metal such as steel. Other materialsinclude, for instance, polymers and the like. The flexible element 404is constructed to provide supplementary tensile strength to withstandspool 200 pulling forces, such as at least 30,000 pounds or more ofpulling force from the spool 200 to the pipe 402 as will be described inthe operation of the pipe removal assembly 100 below.

Referring again to FIG. 4, a lug 408 is coupled along the flexibleelement 404, in one example. The lug 408 is sized and shaped to have alarger profile than the pipe 402. As shown in FIG. 4, the lug 408 has aconical geometry. In another example, the lug 408 has a frusto-coincalgeometry. In still another example, the lug 408 includes cuttingsurfaces that cut at least a portion of the pipe 402 before engagingagainst the pipe 402 and fully transmitting pulling force to remove thepipe from the ground, as described below. In another example, the lug408 includes features for engaging against the pipe 402, such as, butnot limited to hooks, fasteners and the like. The lug 408 engagesagainst the pipe 402, for instance an end of the pipe 402 near thesecond trench 406. In still another example, the flexible element 404engages with the pipe 402 through friction. For instance, the flexibleelement 404 couples with the inner surface of the pipe 402 as theflexible element 404 is navigated through the pipe 402. The flexibleelement 404 contacts the pipe 402 at multiple points on the pipe 402inner surface thereby multiplying the frictional coupling force betweenthe flexible element 404 and the pipe 402. Optionally, the flexibleelement 404 contacts the pipe 402 inner surface at bends and elbows inthe pipe 402. Thus, in one example both friction and the lug 408cooperate to provide the pulling forces necessary to remove the pipe 402from the ground.

In operation, the ground working implement 102 positions the piperemoval assembly 100 in the first trench 400 substantially adjacent tothe pipe 402. The flexible element 404 is navigated through the pipe 402through pushing and/or pulling of the element. In one example, theflexible element 404 is navigated through the pipe 402 from the secondtrench 406 to the first trench 400 and coupled with the spool 200 (FIG.2A) to permit wrapping of the flexible element 404 around the spool. Thelug 408 is already coupled with the flexible element 404 in anotherexample. In yet another example, the flexible element 404 is navigatedthrough the pipe 402 from the first trench 400 to the second trench 406.The lug 408 is then coupled with the flexible element 404.

Referring now to FIGS. 2A and 4, the mechanical advantage system isoperated, for instance the input sprockets 208 are rotated by the motor104 (FIG. 1A). Through the drive chains, the input sprockets 208 rotatethe output sprockets 206 thereby rotating the spool 200. The mechanicaladvantage generated between the input and output sprockets 206, 208generates sufficient torque on the spool 200 to pull the flexibleelement 404 within the pipe 402. As the flexible element 404 is pulledthe lug 408 is pulled into engagement with the pipe 402. The lug 408transmits the pulling force to the pipe 402 and moves the pipe 402through the ground with the flexible element 404. The pipe 402 and theflexible element 404 are both pulled as a composite assembly having thetensile strength of at least the flexible element 404. In one example,the pipe 402 is constructed with ductile material, such as lead, copperand the like. Optionally, the flexible element 404 has a tensilestrength greater than that of the pipe 402 and provides structuralsupport to the ductile pipe 402 by engaging the pipe near an end opposedto the pipe removal assembly 100. In other examples, the flexibleelement 404 engages the ductile pipe 402 at multiple locations along theinner surface of the pipe 402 (e.g., frictionally engages). Pulling theflexible element 404 and the pipe 402 together with the lug 408 puts thepipe 402 in compression and substantially prevents the pipe 402 fromsplitting radially (e.g., because of tensile failure). The flexibleelement 404 thereby ensures substantially the entire pipe is pulled outof the ground. The pipe 402 is retained around the flexible element 404and is pulled out of the ground with the flexible element.

As the composite assembly of the flexible element 404 and the pipe 402are removed both are wrapped around the spool 200 (FIG. 2A). Because theflexible element 404 is coupled with the spool 200 and the pipe 402 iswrapped around the spool 200 the spool pulls both the flexible element404 and the pipe 402 of the composite assembly. The pulling force isthereby transmitted to the pipe 402 through the spool 200 and throughthe flexible element 404 coupled with the pipe 402. Tensile failure ofthe pipe is substantially prevented because while tension is applied tothe pipe 402 through the spool 200, the flexible element 404 pulls thepipe 402 in compression. The flexible element 404 thereby reinforces thepipe 402 with compression as the pipe 402 is pulled by the spool 200.

In one example, the spool 200 includes a slope (i.e., is at leastpartially conical) to ensure the coil of the pipe 402 and the flexibleelement 404 is sequentially wrapped around the spool 200. The pipe 402deforms as it is wrapped around the spool 200 into a compact coil withthe flexible element 404 therein. The flexible element 404 hassufficient flexibility to bend with the pipe, in one example. In anotherexample, the flexible element 404 is deformed with the pipe 402 into thecoil. The coil of the composite assembly is thereby conveniently wrappedand stored on the spool 200 without having to pull lengths of pipe 402out of the trench 400. The coil of the composite assembly including thepipe 402 and the flexible element 404 is then discarded, as describedbelow.

Referring again to FIG. 4, in another example, the lug 408 is sized andshaped to couple with a replacement pipe 410. When the lug 408 is pulledby the pipe removal assembly 100 the replacement pipe 410 is pulledbehind the lug 408. The lug 408 thereby engages with the pipe 402 toensure removal of the pipe 402 while also pulling the replacement pipe410 into position to take the place of the pipe 402. In one example, thepipe removal assembly 100 removes the pipe 402 and positions thereplacement pipe 410 in a single operation. In another example, the piperemoval assembly 100 removes a pipe 402 including for instance lead orcopper and replaces the pipe 402 with a replacement pipe 410.

Referring now to FIGS. 5A-C, the pipe removal assembly 100 is shown inthree different states. In FIG. 5A, the pipe removal assembly 100 isshown in the process of wrapping the composite assembly including thepipe 402 and the flexible element around the spool 200. As describedabove, the spool 200 is rotated and the pipe 402 and the flexibleelement 404 (FIG. 4) are wrapped around the spool 200 into a compactcoil. The coil of the pipe 402 and the flexible element are shownsubstantially wrapped around the spool 200 in FIG. 5B. As shown in FIG.5C, in one example, the coil of the pipe 402 and the flexible element404 are moved off of the spool 200 and discarded.

Referring again to FIG. 5C, the end plate 108 is removed from the spool200 as described above. In one example, the end plate 108 is rotatedwith respect to the spool 200 and the pins 112 (FIG. 1B) are moved intothe larger openings of the slots 110 (FIG. 1B) to facilitate removal ofthe end plate 108. In yet another example, the end plate 108 is removedwith other features, for instance, bolts, clips, retaining pins and thelike. Optionally, the push plate 212 (described above) then engagesagainst the coiled pipe 402 and ejects it off of the spool 200. As shownin FIG. 2A and SC, the push plate 212 is moved over at least a portionof the spool 200 by the thrusting systems 214. In another example, thethrusting systems 214 include hydraulic pistons and cylinders, and areoperated by the hydraulics of the ground working implement 102 to movethe push plate 212. Because the pipe 402 and the flexible element 404are wrapped into the compact coil, the push plate 212 quickly ejects theelement 404 and the pipe 402 in a single step. In yet another example, ataper is included on the spool 200 to facilitate removal of the coiledcomposite assembly. The coiled composite assembly of the flexibleelement 404 and the pipe 402 is compact and easy to remove from the workarea. Additionally, the flexible element 404, such as a metal strand, isinexpensive relative to steel cables and thereby easily replaced afterdiscarding the coiled pipe 402. After ejecting the composite assembly ofthe flexible element 404 and the pipe 402, the end plate 108 is coupledwith the spool 200 to make the pipe removal assembly 100 ready foranother operation.

FIG. 6 shows one example of a method 600 for removing an in-ground pipe,such as pipe 402 shown in FIG. 4. One example of a pipe removal assemblyused in the method 600 is shown in FIGS. 1A-5C as pipe removal assembly100, and is referenced below. At 602, a flexible element 404 isnavigated through the first pipe 402. In one example, the flexibleelement 404 is a strand (e.g. a small number of wires wrapped aroundeach that is stiffer than a cable). The flexible element 404 providessupplementary tensile strength to the pipe 402. Optionally, the flexibleelement has a greater tensile strength than the first pipe. At 604, atleast a portion of the flexible element 404 is coupled with the firstpipe 402. In another example, coupling at least the portion of theflexible element 404 with the first pipe 402 includes engaging a lug 408on the flexible element with the first pipe. In other examples, theflexible element 404 is coupled with the first pipe 402 by frictionalcontact between the flexible element 404 and the interior of the pipe402. At 606, the flexible element 404 and the first pipe 402 are pulledas a composite assembly. In yet another example, the first pipe 402(e.g., lead pipe, copper pipe and the like) is pulled in compressionbetween the point of coupling between the flexible element 404 and thefirst pipe 402 and a proximal end of the flexible element (e.g., nearthe spool 200). While the first pipe 402 is pulled in tension (e.g., bythe spool 200) the flexible element 404 also compresses the first pipe402. The flexible element 404 substantially prevents tensile failure ofthe first pipe 402 by reinforcing the first pipe 402. At 608, thecomposite assembly is removed from the ground surrounding the first pipe402. In still another example, removing the composite assembly from theground includes wrapping the composite assembly around the spool 200.Optionally, wrapping the composite assembly around the spool 200includes deforming the first pipe 402 with the flexible element 404therein into a coil. Although wrapping the composite assembly into acoil provides a convenient collection of the old pipe, in anotheroption, the flexible element 404 and the pipe 402 are pulled by othermeans such as attaching the composite assembly to an implement andmoving the implement in reverse (i.e., away from the flexible elementand pipe).

Several options for the method 600 follow In one example, navigating theflexible element 404 through the first pipe 402 includes pushing theflexible element 404 (e.g., a strand or strip) through the first pipe402. In another example, coupling at least the portion of the flexibleelement 404 with the first pipe 402 includes engaging a pipe splitter onthe flexible element with the first pipe. The method 600 includes, inyet another example, discarding the composite assembly.

FIG. 7 shows another example of a method 700 for removing an in-groundpipe. As described above, one example of a pipe removal assembly used inthe method 700 is shown in FIGS. 1A-5C as pipe removal assembly 100, andis referenced below. At 702 a flexible element 404 is navigated througha first pipe 402. For example, the flexible element 404 is a strandincluding a small number of wires that provides stiffness to the strandand allows for pushing and pulling through the first pipe 402. Theflexible element 404 provides supplementary tensile strength to the pipe402 and substantially prevents tensile failure of the pipe 402.Optionally, the flexible element 404 has a tensile strength at leastgreater than the tensile strength of the first pipe 402. At 704, theflexible element 404 is coupled with the first pipe 402. In anotherexample, coupling the flexible element 404 with the first pipe 402includes engaging a lug 408 against the first pipe 402, and the lug 408is coupled with the flexible element 404. In other examples, theflexible element 404 is coupled to the interior of the pipe 402 byfrictional contact therebetween. At 706, the flexible element 404 andthe first pipe 402 are wrapped around a spool 200 as a compositeassembly. In yet another example, wrapping the flexible element 404 andthe first pipe 402 as the composite assembly includes pulling the firstpipe 402 in compression between the point of coupling between theflexible element 404 and the first pipe 402 (e.g., at the lug and/or atfrictional contact between the flexible element 404 and the interior ofthe pipe 402) and a proximal end of the flexible element 404 (e.g. nearthe spool 200). The flexible element 404 reinforces the first pipe 402by applying compression thereto while the first pipe 402 is pulled(e.g., by the spool 200). Pulling the first pipe 402 in compressionincludes substantially preventing tensile failure of the first pipe 402,in still another example. Optionally, the first pipe 402 pulled incompression includes a pipe including lead (e.g., a pipe havinginsufficient tensile strength to be pulled out of the ground by itself).

Several options for the method 700 follow. In one example, the method700 includes rotating the spool 200, and the flexible element 404 iscoupled with the spool 200. The spool 200 is rotated with a chain drive(e.g., including input and output sprockets 208, 206), in anotherexample. In yet another example, the spool 200 is rotated with aplanetary gear assembly. Where the first pipe 402 is pulled incompression (described above) the method 700 may include pulling asecond pipe 410 behind the first pipe 402, in still another example.Optionally, wrapping the flexible element 404 and the first pipe 402 asthe composite assembly includes deforming the composite assembly into acoil. In a further example, the method 700 includes removing thecomposite assembly from the spool 200 (e.g., by pushing the compositeassembly over the spool 200 with a push plate 212.

FIG. 8 shows yet another example for a method 800 for removing anin-ground pipe. As described above, one example of a pipe removalassembly used in the method 800 is shown in FIGS. 1A-5C as pipe removalassembly 100, and is referenced below. At 802, a flexible element 404 isnavigated through a first pipe 402. At 804, a lug 408 is engaged againstthe first pipe 402, and the lug 408 is coupled with the flexible element404. At 806, the flexible element 404 is coupled with a spool 200 of thepipe removal assembly 100. At 808, the spool 200 is rotated. At 810, theflexible element 404 is pulled with the first pipe 402 as a compositeassembly. In another example, the flexible element 404 reinforces thefirst pipe 402 by applying compression thereto while the first pipe 402is pulled in tension (e.g., by the spool 200). Pulling the first pipe402 in compression includes substantially preventing tensile failure ofthe first pipe 402, in still another example. At 812, the compositeassembly is wrapped around the spool. At 814, the composite assembly ismoved (e.g., pushed or pulled) off of the spool. At 816, the compositeassembly is discarded.

Several options for the method 800 follow. In one example, navigatingthe flexible element 404 through the first pipe 402 includes pushing astrand through the first pipe 402. In another example, rotating thespool 200 includes rotating the spool 200 with a mechanical advantagesystem that has a greater output torque than an input torque. Forinstance, rotating the spool 200 includes rotating the spool 200 with achain drive (e.g., with input and output sprockets 208, 206). In yetanother example, pulling the flexible element 404 and the first pipe 402as the composite assembly includes pulling the first pipe 402 incompression between the point of coupling between the flexible element404 and the first pipe 402 and a proximal end of the flexible element404 (e.g., near the spool 200).

CONCLUSION

The above described examples of pipe removal methods and assembliesprovide devices and methods usable to remove in-ground pipes includingpipes having a low tensile strength, such as lead and copper pipes. Thepipe removal assembly pulls the pipe with the flexible element as asingle composite assembly. The flexible element engages with the pipe ata location remote from the pipe removal assembly and pulls the pipe incompression between that location and the pipe removal assembly. At thesame time, the pipe is pulled in tension (e.g., by the spool). Thecompression provided by the flexible element reinforces the pipe andsubstantially prevents tensile failure of the pipe. The pipe removalassembly including the flexible element thereby substantially preventsradial fracture of the pipe (i.e., fracture along the pipecircumference) and ensures the pipe is removed without leaving afractured portion of the pipe behind.

Further, the pipe removal assembly wraps the composite assembly of thepipe with the flexible element therein around the spool. The compositeassembly is deformed as it wraps around the spool and forms a compactcoil that is easily discarded. The flexible element, for instance ametal strand that is inexpensive and easily replaceable remains withinthe coiled pipe and is discarded with the pipe. In one example, the piperemoval assembly includes a push plate that ejects the coiled pipe andflexible element off of the spool. The removed pipe is manageably storedon the spool and discarded as a compact coil thereby avoiding storage,transportation and disposal of cumbersome lengths of removed pipe.

Further still, the lug that couples the flexible element with the pipeincludes, in one example, a feature sized and shaped to couple areplacement pipe thereon. 5 The replacement pipe is pulled into positionbehind the lug while the original pipe with the flexible element ispulled and wrapped around the spool. The pipe removal assembly therebyefficiently removes and replaces pipes in a single step.

Although selected advantages are described above, the list is notintended to be exhaustive. Further, the above description is intended tobe illustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. It should be noted that embodiments discussed indifferent portions of the description or referred to in differentdrawings can be combined to form additional embodiments of the presentapplication. The scope of the invention should, therefore, be determinedwith reference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A pipe removal assembly comprising: a spool adapted to couple aflexible element; a push plate extending around at least a portion ofthe spool, wherein the push plate is moveable along a longitudinalsurface of the spool; a lug adapted to couple with the flexible element,wherein the lug is sized and shaped to engage against a pipe; andwherein the spool is adapted to wrap the pipe with the flexible elementtherein around the spool as a composite assembly coil, and the pushplate is adapted to move the composite assembly coil off of the spool.2. The pipe removal assembly of claim 1, wherein the spool includes aremovable end plate extending around at least a portion of the spool. 3.The pipe removal assembly of claim 2, wherein the removable end plate isremote from the push plate.
 4. The pipe removal assembly of claim 1,wherein the spool includes a frusto-conical geometry.
 5. The piperemoval assembly of claim 1, wherein the push plate is coupled with atleast one thrusting system including a hydraulic piston and a hydrauliccylinder.
 6. The pipe removal assembly of claim 1, further comprising amechanical advantage system and a motor adapted to rotate the spool. 7.The pipe removal assembly of claim 6, wherein the motor includes ahydraulic motor.
 8. The pipe removal assembly of claim 6, wherein themechanical advantage system includes at least one sprocket coupled witha chain.
 9. The pipe removal assembly of claim 1, wherein the lug issized and shaped to couple with a replacement pipe.
 10. The pipe removalassembly of claim 1, wherein the flexible element is a metal strand.